Dec 19 (Reuters) - An overnight slump in oil prices and a softer dollar helped lift emerging currency and stock markets on Wednesday as investors waited for the U.S. Federal Reserve’s last policy meeting of 2018.

Currencies of major crude importers including India’s rupee , Turkey’s lira and Indonesia’s rupiah pushed the MSCI’s index for developing world currencies higher for the third day in a row.

Oil prices stabilised on Wednesday after one of their biggest falls for years, but remained under pressure from oversupply and concern that a slowing global economy would depress demand for fuel.

“The oil plunge has provided relief to the distressed capital markets in the region,” said Stephen Innes, head of Asia-Pacific trading at OANDA.

The dollar slid as investors bet the Fed would signal plans to slow its pace of interest rate raises, propping up emerging market currencies including South Korea’s won and South Africa’s rand, which chalked up some of the biggest gains, up 0.7 percent.

MSCI’s index for emerging market stocks snapped a three-day losing streak with robust gains in Asian indexes barring mainland China , which fell more than 1 percent led by losses in healthcare and energy companies.

“Equities are a little complicated today but it is sometimes attractive to own undervalued equities when the currency is appreciating,” said Stephen Innes.

Indian stocks rose in line with the bond market after the central bank’s announcement of a hefty open market bond purchase scheduled for January.

Stocks on Moscow’s MOEX index continued to fall for the fourth day in a row with plunging oil prices weighing on index-heavy energy stocks.

In Eastern Europe, Romania’s blue chip index fell to its lowest level in more than six months, wiping out almost all of its 2018 gains after the Social Democrat government announced new tax plans for banks and energy companies and made private pension funds optional.